Question: What do the following two equations represent? $-5x+5y = 1$ $-25x-25y = -4$
Answer: Putting the first equation in $y = mx + b$ form gives: $-5x+5y = 1$ $5y = 5x+1$ $y = 1x + \dfrac{1}{5}$ Putting the second equation in $y = mx + b$ form gives: $-25x-25y = -4$ $-25y = 25x-4$ $y = -1x + \dfrac{4}{25}$ The slopes are negative inverses of each other, so the lines are perpendicular.